It turns out that not only is the U.S. Postal Service delivering on Saturdays, but, under a new deal with Amazon, they will be making some deliveries on Sundays, as well.

Announced, fittingly, on Sunday evening, Amazon said that Prime customers in New York and Los Angeles can now get packages delivered via the local postman on Sundays. Amazon said the service will expand to “a large portion of the U.S. population” next year, including those in Dallas, Houston, New Orleans and Phoenix, among other cities.

“If you’re an Amazon Prime member, you can order a backpack for your child on Friday and be packing it for them Sunday night,” Amazon VP Dave Clark said in a statement. “We’re excited that now every day is an Amazon delivery day, and we know our Prime members, who voraciously shop on Amazon, will love the additional convenience they will experience as part of this new service.”

A statement from the Post Office suggests that the service may not be limited to Amazon.

“As online shopping continues to increase, the Postal Service is very happy to offer shippers like Amazon the option of having packages delivered on Sunday,” said Postmaster General Patrick R. Donahoe. “With this new service, the Postal Service is now delivering packages seven days a week in select cities. Customers can expect the same reliable and valued service that the Postal Service currently provides.”

An Amazon representative said that the Sunday service is currently only available to Amazon customers.